Well, i upgraded my ipad 3 to a 4 (as the three was slowing down sporadically since ios 6) the 4 does exactly the same. I called apple asking for help on it, if it was a known issue etc. A very nice lady arranged for a replacement to be sent out, got this in 2 days. However i get exactly the same slowdown on it (stuttering then quick again) with no apps installed just an empty ipad. More over the screen is shocking, very poor brightness and a blue line down the side (and some dust under the screen) i emailed the lady from apple, 1 minute later i get a call. They are picking up the replacement pad, as a good will gesture (i didn't even ask) they are refunding £80 into my card. She also admitted that ios 6 isn't very good, she doesn't know how long it will take to fix it or IF it can be made as quick as 5.1.1 was on my 3. She apologised again. So down side is the sporadic slowness on my 4 but the upside is a very good customer service experience. A rare thing these days! Just thought i would share as i didn't expect such good service after all I have heard about Apple.